Process of precipitating metals.



No. 876,346. PATENTED JAN. 14, 1908. J. E. GRBENAWALT. PROCESS 0F PREGIPITATING METALS. APPLICATION FILED APR.3,1905.

2 sHBETSsHBET 1.

PATENTED JAN.l 14, 1908.. J. E. GRBENAWALT.

PROCESS 0F PRBGIPITATING METALS.

APPLICATION FILED APRA. 1905.

2 SHEETS-SHEET 2.

I lull' @brown/1j JOHN E. GREENAWALT, OFDENVER, COLORADO.

i PROCESS OF PRECIPITATING METALS.

Specification of Letters Patent.

Patented Jan. 14, 1908.

Application filed April 3. 1905. Serial No. 263.621-

To all whom 'it may concern:

Be it known that l, JOHN E.- GREENAWALT, a citizen of the United States, residing at the city and county of Denver and State of Colorado, have invented a certain new and useful Process of Precipitating Metals; and I do declare the following to be a full, clear, and

exact description Vof the invention, such as willk enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, andto the letters and igures of' reference marked thereon, which form a part of this specification.

My invention relates to a process for the precipitation of metals from a solution containing the dissolved metallic values.

The special object of the invention is the thorough and economical precipitation of gold and silver from solutionscontaining the same, particularly from chlorid solution obtained in the treatment of gold and silver' ores by cli-lorin.

This is accomplished by preci itating the gold and silver upon a nieta lic sponge or shavings consisting preferably of lead with from one-half'of one per cent. to on'e per cent. of zinc.

The object in forming this alloy, is to produce acompound that is slowly and graduallyT dissolved in the solution. The action between the solution and the metallic precipialso determined that lead with a smallamount of easily soluble metal such as zinc,

forms an excellent precipitant for gold andA silver, and this is particularly true if the solution be brought up to a comparatively high temperature of say to one hundred thirty degrees Fahrenheit, or higher. use of the electric current in connection with the rocess is preferable in as much as the precipitation is accomplished more rapidly and completely, and further results in greater economy from' the fact that a large proportion of the lead dissolved can be repiecipitated upon the lead sponge.

lsilver-carrying solution G from a The l The accompanying drawing illustrates suitable apparatusior practicing my 1mproved process. This apparatus, however, is

not claimed iii this application but in a conipanioii application filed at the same time.

ln this drawing, Figure 1 is a sectional view of three precipitating cells, the same being connected in operative relation, whcreby the solution is made to pass through them successively. It is evident that any desired number of these cells may be einployed. Fig. 2 is a top plan view of the saine.

The same reference characters indicate the same parts in all the views.

Let A, B and C designate three cells which are precisely of the saine construction, but given different reference characters for convenience of description. In the lower part of each of these cells isy placed a perforated floor or partition 2 upon which the metal sponge or shavings employed iii the process of precipitation are placed. In the upper part of this cell is sup oited ,a jar S coniposed of porous materia in which is placed a carbon anode 7 connected with the positive wire 6 of an electric circuit. The jar S is' suspended from the top of each cell by means of rods D which pass through ears E located on opposite sides of each jar. As shown in the drawing these supporting rods rest on and roject slightly beyond the top of each cell t ie cells being o en.

The mass of meta shavings 3, constitutes the cathode element of the apparatus with which aconductor 9 leading from the negative pole of the electric source is connected. In 'order to maintain a perfect electrical connection between the cathode element and the negativewire .of the source,.1 place within each cell just above the perforated floor or diaphragm, a metal ring F with which the negative wii'e or conductor is directly connected.

ln carrying out the process, the orold and leaching vat (not shown), ilows into the cell .A through a pipe 1, delivering the solution near the bottom of the cell and just below the perforated floor 2 which supports the metallic sh'avings 3 as aforesaid. It then flows through the perforated floor, through and among the metallic shavings and finally is discharged from the cell A through a pipe 5 into the cell B at a similarl point; and after passing through l jar S into the solution and 'finally to the methe lead from the shavings enters the soluthe last lnamed cell in the same manner as through the cell A, it may be discharged from the top of the cell B through'a pipe 5a into a cell C; after passing through the cell C, if the metallic values have not been completely precipitated, the process may be continued by passing the solution through any desired number of cells of substantially the same construction as heretofore stated. T he outlet from the cell C is designated at 5C in the drawing.

The electric current is supplied through the positive wire G to the carbon anode 7 from which it passes through the porous tallic sponge or shavings 3 which constitute thefcathode :of the electrolytic cell. The shavin gs are brought into direct contact with the negative wire 9 as heretofore explained whereby the circuit is completed.

ltis desirable to suspend the anode element at some distance above the cathode sponge, as this arrangement gives a much better distribution of the current through the" entire mass of shavings, whereby the gold and silver values are deposited upon the shavings or cathode element. Some of tion as chlorid (when the solution is a strong brine) and is precipitated by the current when the amount of gold or silver in the solution is exhausted or comparatively small. This is very desirable since if the current did not precipitate the lead, it would precipitate some of the' baser elements which would have a tendency to clog the shavings and introduce undesirable products into the precipitate.

ln practice a black pulverulent slime is produced, consisting principally of lead, silver and gold which is readily melted into bullion and the metals separated. The recovered lead is then melted, and a small amount of Zinc added, after vwhich the lead mass is cut again into shavings when it is ready for reuse. The shavings are preferably cut about one-sixteenth of an inch wide and one-hundredth of an inch thick.- The precipitated slime settles in the lower chamber of the cell. l have found that with a depth of six inches of shavings, an electric current of five amperes for every cubic foot of shavings, gives excellent results;

described my invention, what less of Zinc with the lead and then vfinely dividing said alloy, the solution being heated. 3. 'The process of precipitating gold and silver from their solutions which consists in passing a solution around and among the metallic surfaces which are slightly soluble in the solution and constituting the cathode element of an electrolytic cell, applying an electric current of a low voltage for the precipitation of the gold and silver and then applying a current of higher voltage to precipitate the metal of the cathode element which has'passed into solution during the time of precipitating the gold and silver.

4. The process of precipitating gold and silver from their solutions by' passmg the solutions around and among metallic surfaces which are slightly soluble in the solution and constituting the cathode element of an electrolytic cell, and applying an electric current to precipitate the gold and silver and also simultaneously reprecipitate the cathode element which has passed into solution` 5. The process of precipitating gold and silver from their solutions which consists in passing the solution through a sponge or mass of metallic shavings consisting of lead with one per cent..or less of Zinc alloyed therewith and then melting the precipitate, separating the lead from the gold and silver and again using the lead for precipitating purposes as described` In testimony whereof I afliX my signature in presence of two witnesses.

JOHN E. GREENAlVALT. Vitnesses :v

DENA NELSON, A. J. GBRIEN. 

